module.exports = function randomString() {  
    let str = 'abcdefghijklmnopqrstuvwxyz9876543210';
    let tmp = '',
        i = 0,
        l = str.length;
    for (i = 0; i < 32; i++) {
      tmp += str.charAt(Math.floor(Math.random() * l));
    }
    return tmp;
  }